Super abrasive grain wire saw winding structure, super abrasive grain wire saw cutting device, and super abrasive grain wire saw winding method

ABSTRACT

A superabrasive wire saw-wound structure includes a superabrasive wire saw ( 10 ) formed with an average diameter D and a reel ( 1 ). The superabrasive wire saw ( 10 ) includes a core wire ( 11 ), a bonding material ( 12 ) surrounding a surface of the core wire ( 11 ), and a plurality of superabrasive grains ( 13 ) bonded to the surface of the core wire ( 11 ) with the bonding material ( 12 ). The reel ( 1 ) includes a peripheral surface ( 2 ) having one end ( 3 ) and the other end ( 4 ). The superabrasive wire saw ( 10 ) which is to be unreeled successively toward a workpiece is wound around the peripheral surface ( 2 ) reciprocatingly between the one end ( 3 ) and the other end ( 4 ) to be multi-layered. A pitch P for winding the superabrasive wire saw ( 10 ) around the peripheral surface ( 2 ) between the one end ( 3 ) and the other end ( 4 ) satisfies a relation of D&lt;P&lt;2D. According to the present invention, there can be provided a superabrasive wire saw-wound structure, a cutting device with a superabrasive wire saw, and a method of winding a superabrasive wire saw which can reduce damage to a bonding material and falling of a superabrasive grain.

TECHNICAL FIELD

The present invention generally relates to a superabrasive wiresaw-wound structure, a cutting device with a superabrasive wire saw, anda method of winding a superabrasive wire saw, and more particularly, toa bonded-abrasive type superabrasive wire saw-wound structure, a cuttingdevice with a superabrasive wire saw, and a method of winding asuperabrasive wire saw which are used for slicing a silicon ingot intosilicon wafers, and performing a cutting process on various materialssuch as metal, resin, ore, glass, sapphire, rock crystal, SiC, andcompound semiconductor.

BACKGROUND ART

Conventionally, a bonded-abrasive type diamond wire saw, which hasdiamond abrasive grains bonded to the surface of a core wire, has beenproposed as an example of a superabrasive wire saw. With the diamondwire saw, a material such as a metal can be cut extremely cleanly. Inaddition, there is no need for a slurry having an abrasive fluid andabrasive grains blended; instead, a water-soluble or water-insolublecutting fluid can be used. Therefore, contamination of a cutting deviceand its vicinity due to a sludge spattered during cutting can beprevented, and thus working environment can be improved.

In addition, the diamond wire saw can be produced to have a long lengthsuch as at least several kilometers. Therefore, a plurality of cuttingprocesses can simultaneously be performed, and accordingly, there can beobtained a cutting rate of at least several times as high as that of amulti-wire saw type using a slurry. Such a bonded-abrasive typesuperabrasive wire saw is disclosed in Japanese Patent Laying-Open Nos.8-126953 and 9-155631, International Publication No. WO 98/35784, andothers.

In addition, Japanese Patent Laying-Open No. 4-351222 discloses abonding wire winding which is wound reciprocatingly to be multi-layeredsuch that it is unreeled smoothly during a bonding operation. For thebonding wire winding disclosed in Japanese Patent Laying-Open No.4-351222, a bonding wire wound around a spool from one end to the otherend thereof and the bonding wire further wound around the spool from theother end to the one end thereof are set to cross at an angle of atleast 0.03°.

In addition, Japanese Patent Laying-Open No. 2002-18517 discloses awire-winding device for the purpose of preventing failure in reeling thewire around a bobbin. The wire-winding device disclosed in JapanesePatent Laying-Open No. 2002-18517 is a device for winding an electricwire, a wire, and a cable around a bobbin. The wire-winding device isprovided with a bobbin flange detection sensor which is capable ofdetecting the position of the flange. Every time the sensor detects theflange position, a moving direction of a traverser which serves to guidethe wire is reversed.

In addition, Japanese Patent Laying-Open No. 2000-349120 discloses amethod of winding a bonding wire for a semiconductor element for thepurpose of prolonging the life of a guide, whose damage causes a flaw inthe wire. In the winding method disclosed in Japanese Patent Laying-OpenNo. 2000-349120, a non-rotary type winding guide is used. The windingguide is formed of a hard base material coated with a diamond-likecarbon film.

When a cutting process is performed using the superabrasive wire sawabove, the superabrasive wire saw is provided in a reeled-up state, fromwhich the same is unreeled toward or reeled up from a workpiece.Therefore, in order to make the superabrasive wire saw attachable to acutting device, it is necessary to wind the same around a reelappropriate for the cutting device. FIG. 8 shows a cross section of asuperabrasive wire saw wound around a reel in a conventional manner.

Referring to FIG. 8, a superabrasive wire saw 310 includes a core wire311, and a plurality of superabrasive grains 313 bonded to a surface ofcore wire 311 with a bonding material 312. Unlike a loose-abrasive type,superabrasive grain 313 is provided to project from a surface of bondingmaterial 312. Superabrasive wire saw 310 is wound around a surface of areel 301 shaped like a cylinder reciprocatingly between the both ends ofthe surface to be multi-layered. Superabrasive wire saw 310 is woundwith a certain pitch between the both ends of the surface of reel 301,and adjacent superabrasive wire saws 310 are in contact with each other.

When superabrasive wire saw 310 is wound around reel 301 as such,adjacent superabrasive wire saws 310 cause a friction therebetween, withthe result that bonding material 312 is damaged by superabrasive grains313. Furthermore, by an intense collision between superabrasive grains313, superabrasive grains 313 disadvantageously fall down from thesurface of core wire 311. Such problems also occur during a cuttingprocess in which superabrasive wire saw 310 is unreeled toward or reeledup from a workpiece in a state similar to that shown in FIG. 8.

DISCLOSURE OF THE INVENTION

An object of the present invention is to solve the problems above, andprovide a superabrasive wire saw-wound structure, a cutting device witha superabrasive wire saw, and a method of winding a superabrasive wiresaw which can reduce damage to a bonding material and falling ofsuperabrasive grains.

A superabrasive wire saw-wound structure according to the presentinvention includes a superabrasive wire saw formed with an averagediameter D, and a reel portion. The superabrasive wire saw includes acore wire, a bonding material surrounding a surface of the core wire,and a plurality of superabrasive grains bonded to the surface of thecore wire with the bonding material. The reel portion includes aperipheral surface having one end and the other end. The superabrasivewire saw, which is to be unreeled successively toward a workpiece, iswound around the peripheral surface reciprocatingly between the one endand the other end to be multi-layered. A pitch P with which thesuperabrasive wire saw is wound around the peripheral surface betweenthe one end and the other end satisfies a relation of D<P<2D.

With the superabrasive wire saw-wound structure configured as such,since pitch P with which the superabrasive wire saw is wound is largerthan average diameter D of the superabrasive wire saw, when thesuperabrasive wire saw is wound around the surface of the reel portion,an intense friction between a superabrasive wire saw which is beingwound and a superabrasive wire saw which has already been wound in anadjacent position can be prevented. In addition, since pitch P issmaller than 2D, when the superabrasive wire saw is wound around thesurface of the reel portion, a superabrasive wire saw which is beingwound does not enter a gap between the adjacent superabrasive wire sawswhich have already been wound in a lower layer. As a result, when thesuperabrasive wire saw is unreeled again from the reel portion, anintense friction between the superabrasive wire saws can be prevented.For the reasons above, according to the present invention in which pitchP is set within an appropriate range, damage to the bonding material andfalling of the superabrasive grains can be reduced.

Preferably, pitch P further satisfies a relation of 1.1D<P<(3^(1/2)) D.With the superabrasive wire saw-wound structure configured as such, theeffects described above can more effectively be obtained. In addition,since pitch P is smaller than (3^(1/2)) D, a superabrasive wire sawwhich is being wound is not brought into contact with a superabrasivewire saw which has already been wound two layers below. Therefore,damage to the bonding material and falling of the superabrasive grainscaused by the contact between the superabrasive wire saws can bereduced.

Preferably, the core wire having an average diameter d1, thesuperabrasive grain having an average diameter d2, and average diametersd1 and d2 satisfy a relation of 0.02<d2/d1<0.5. With the superabrasivewire saw-wound structure configured as such, since d2/d1 is smaller than0.5, the average diameter of the superabrasive grain does not become toolarge with respect to the average diameter of the core wire. Therefore,the bonding material applied at the surface of the core wire canreliably hold the superabrasive grains. In doing so, falling of thesuperabrasive grains can further be reduced. In addition, since d2/d1 islarger than 0.02, the superabrasive grains have a certain degree ofsize. Therefore, there can be prevented falling of the superabrasivegrains from the surface of the core wire due to lack of ability toendure a processing stress during cutting. In addition, since thesuperabrasive grains are not too fine, sharpness of the superabrasivewire saw is not extremely reduced.

Preferably, the bonding material includes at least one selected from thegroup consisting of a resin bond, an electrodeposition, a metal bond,and a vitrified bond. With the superabrasive wire saw-wound structureconfigured as such, the superabrasive grains can reliably be held at thesurface of the core wire, and falling thereof can be prevented.

The cutting device with a superabrasive wire saw according to thepresent invention includes a superabrasive wire saw supplier provided byusing any of superabrasive wire saw-wound structures described above.With the cutting device with a superabrasive wire saw configured assuch, a desired cutting process can be performed by using thesuperabrasive wire saw with which damage to the bonding material andfalling of the superabrasive grains are reduced.

The method of winding a superabrasive wire saw according to the presentinvention includes the step of preparing a superabrasive wire saw formedwith an average diameter D and a reel portion including a peripheralsurface having one end and the other end. The superabrasive wire sawincludes a core wire, a boding material surrounding a surface of thecore wire, and a plurality of superabrasive grains bonded to the surfaceof the core wire with the bonding material. The method of winding asuperabrasive wire saw further includes the step of winding thesuperabrasive wire saw around the peripheral surface reciprocatinglybetween the one end and the other end to be multi-layered. The step ofwinding the superabrasive wire saw includes the step of winding thesuperabrasive wire saw such that a pitch P for winding the superabrasivewire saw between the one end and the other end satisfies a relation ofD<P<2D.

According to the method of winding a superabrasive wire saw configuredas such, since pitch P with which the superabrasive wire saw is wound islarger than average diameter D of the superabrasive wire saw, when thesuperabrasive wire saw is wound around the surface of the reel portion,an intense friction between a superabrasive wire saw which is beingwound and a superabrasive wire saw which has already been wound in anadjacent position is prevented. In addition, since pitch P is smallerthan 2D, when the superabrasive wire saw is wound around the surface ofthe reel portion, the superabrasive wire saw which is being wound doesnot enter a gap between the adjacent superabrasive wire saws which havealready been wound in a lower layer. In doing so, when the superabrasivewire saw is unreeled again from the reel portion, an intense frictionbetween the superabrasive wire saws can be prevented. For the reasonsabove, according to the present invention in which pitch P is set withinan appropriate range for winding the superabrasive wire saw, damage tothe bonding material and falling of the superabrasive grains can bereduced.

Preferably, the step of winding the superabrasive wire saw includes thestep of winding the superabrasive wire saw with winding tensioncorresponding to 5% to 50%, both inclusive, of a breaking strength ofthe superabrasive wire saw. According to the method of winding asuperabrasive wire saw configured as such, since the winding tension isat least 5% of the breaking strength of the superabrasive wire saw, thesuperabrasive wire saw once wound around the reel portion does notloosen with time. Furthermore, since the winding tension is at most 50%of the breaking strength of the superabrasive wire saw, damage to thebonding material due to engagement of the superabrasive wire saws isprevented.

As described above, according to the present invention, there can beprovided a superabrasive wire saw-wound structure, a cutting device witha superabrasive wire saw, and a method of winding a superabrasive wiresaw which can reduce damage to a bonding material and falling ofsuperabrasive grains.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing a superabrasive wire saw windinghaving a superabrasive wire saw-wound structure in accordance with afirst embodiment of the present invention.

FIG. 2 is a schematic view showing an enlarged superabrasive wire sawshown in FIG. 1.

FIG. 3 is a schematic view showing a cross section taken along a lineIII-III shown in FIG. 2.

FIG. 4 shows a cross section taken along a line IV-IV shown in FIG. 1.

FIG. 5 is a schematic view showing a winding device for producing thesuperabrasive wire saw winding shown in FIG. 1.

FIG. 6 is a schematic view showing a contour of the superabrasive wiresaw wound around a reel.

FIG. 7 is a perspective view showing a cutting device with asuperabrasive wire saw in accordance with a third embodiment of thepresent invention.

FIG. 8 shows a cross section showing a superabrasive wire saw woundaround a reel in a conventional manner.

BEST MODES FOR CARRYING OUT THE INVENTION

Embodiments in accordance with the present invention will now bedescribed in reference to the drawings.

First Embodiment

Referring to FIG. 1, a superabrasive wire saw 10 is wound around aperipheral surface of a reel 1 shaped like a cylinder to bemulti-layered. As described in detail below, in the superabrasive wiresaw-wound structure in the present embodiment, a pitch P with whichsuperabrasive wire saw 10 is wound around the peripheral surface is setwithin a predetermined range.

Superabrasive wire saw 10 is used for slicing a silicon ingot intosilicon wafers, and performing a cutting process on cemented carbide,cermet, ceramics, germanium, ferrite, Sendust, alnico, samarium cobalt,neodymium magnet, glass, rock crystal, sapphire, stone material,firebrick, tile, resin material, fiber-glass reinforced plastic (FRP),carbon fiber reinforced plastic (CFRP), graphite, grindstone, preciousstone, metallic material, and others.

A part of FIG. 2 shows a longitudinal cross section of the superabrasivewire saw. Referring to FIGS. 2 and 3, superabrasive wire saw 10 includesa core wire 11 extending linearly, a bonding material 12 covering asurface 11 a of core wire 11, and a plurality of superabrasive grains 13bonded onto surface 11 a with bonding material 12. Superabrasive grain13 is formed of a diamond abrasive grain, for example, and is providedsuch that a portion thereof protrudes from a surface 12 a of bondingmaterial 12.

Superabrasive wire saw 10 has an average diameter D, which is determinedas follows: randomly selecting three points of measurement spaced apartin the longitudinal direction of superabrasive wire saw 10; measuring adiameter of superabrasive wire saw 10 in three directions at each ofthese points to obtain nine measurements in total; and averaging theobtained measurements.

An average diameter d1 of core wire 11 is preferably 0.01 mm to 1 mmboth inclusive, and can also be determined by the measuring methoddescribed above. For core wire 11, any one of a steel wire, acopper-plated steel wire, and a brass-plated steel wire can be used.

For the steel wire, a piano wire is most preferable because it caneasily be formed into an ultrafine wire and has high strength. Althoughthe piano wire can be used as it is, it is preferable to perform thereona surface treatment such as copper plating or brass plating in orderthat it is easily preserved and that adhesion of a resin bond thereto isimproved to enhance ability to hold the superabrasive grains.

For the core wire made of other materials, it is possible to use a solidwire or stranded wire of any one of carbon fiber, aramid fiber, boronfiber, and glass fiber. Alternatively, it is also possible to use astranded wire formed by blending at least any two of carbon fiber,aramid fiber, boron fiber, and glass fiber. Furthermore, it is alsopossible to use as the core wire a stranded wire formed by adding asteel wire to each of these stranded fibers above.

Given that superabrasive grain 13 has an average diameter d2, averagediameter d1 of core wire 11 and average diameter d2 of superabrasivegrain 13 preferably satisfy a relation of 0.02<d2/d1<0.5. In this case,it is possible to use core wire 11 having average diameter d1 of 0.11mm, 0.13 mm, 0.155 mm, 0.16 mm, 0.18 mm, 0.2 mm, or 0.5 mm, for example.At the same time, it is possible to use superabrasive grain 13 havingaverage diameter d2 of 0.010 mm, 0.012 mm, 0.032 mm, 0.042 mm, or 0.055mm, for example. By using superabrasive grains 13 and core wire 11satisfying such a relation, superabrasive grains 13, which are reliablyheld on surface 11 a, can contribute to a cutting process. At the sametime, clear-cut can be obtained.

For bonding material 12, a resin bond, an electrodeposition, a metalbond, or a vitrified bond can be used. For bonding material 12, it isalso possible to use various bonding materials such as a composite bondformed of a resin bond and a metal bond, and a composite bond formed ofa resin bond and a vitrified bond. In particular, the effects of thepresent embodiment can remarkably be exhibited by using a resin bond ora composite bond mainly composed of a resin bond.

From a viewpoint of coefficient of elasticity, softening temperature,formability, and physical properties, preferable examples of resinapplicable to the resin bond include alkyd resin, phenol resin, formalinresin, polyurethane resin, polyester resin, polyimide resin, epoxyresin, melamine resin, urea resin, unsaturated polyester resin, acrylicresin, polyesterimide resin, polyamid-imide resin, polyester urethaneresin, bismaleimide resin, bismaleimide triazine resin, cyanato esterresin, polyetherimide, polyparabanic acid, aromatic polyamide, andothers.

The electrodeposition refers to bonding material 12 electrodeposited onsurface 11 a of core wire 11. For example, nickel (Ni) plating isapplied to surface 11 a for serving as bonding material 12. If a metalbond is used as bonding material 12, appropriate metal powder andsuperabrasive grains 13 are made into mixed powder, which is sintered tosurface 11 a of core wire 11.

FIG. 4 schematically shows only a portion of superabrasive wire saw 10actually wound around reel 1. Referring to FIG. 4, reel 1 has aperipheral surface 2 and an inner wall 5 extending from each end ofperipheral surface 2 in the perpendicular direction. At the points whereperipheral surface 2 crosses inner walls 5, one end 3 and the other end4 are defined, respectively.

Superabrasive wire saw 10 is initially wound around peripheral surface 2from one end 3 to the other end 4 with pitch P (superabrasive wire saws101 a, 101 b, 101 c and 101 d in a first layer). After the superabrasivewire saws for the first layer are wound to the other end 4,superabrasive wire saw 10 is wound from the other end 4 to one end 3with pitch P over the superabrasive wire saws already wound(superabrasive wire saws 102 a, 102 b, 102 c and 102 d in a secondlayer). Furthermore, superabrasive wire saw 10 is wound from one end 3to the other end 4 in a third layer, wound from the other end 4 to oneend 3 in a fourth layer, and so on, in order to be wound reciprocatinglybetween one end 3 and the other end 4 with pitch P to be multi-layered.

Pitch P with which superabrasive wire saw 10 is wound around peripheralsurface 2 between one end 3 and the other end 4 satisfies a relation ofD<P<2D. Pitch P preferably satisfies a relation of 1.1D<P<1.9D.

Referring to FIG. 5, a winding device 21 includes a motor 22 as a firstdriver having a rotating shaft on which reel 1 is mounted for rotatingreel 1 at a predetermined rate, a traverser 24 placed in the vicinity ofreel 1 for guiding superabrasive wire saw 10 which is to be wound aroundreel 1, and a motor 25 as a second driver having traverser 24 connectedthereto for reciprocating the same.

The rotating shaft of motor 25 is connected to a ball screw 26, andtraverser 24 is connected to a nut of ball screw 26. By forward/reverserotation of motor 25 at a predetermined cycle, traverser 24 canreciprocate in the directions shown in an arrow 27. On a path wheresuperabrasive wire saw 10 is unreeled toward reel 1, a tension meter 23is provided for measuring winding tension of superabrasive wire saw 10.Winding device 21 is also provided with a controller, which is notshown, for suitably controlling rotating rates of motors 22 and 25,respectively.

A method of winding superabrasive wire saw 10 around reel 1 by usingwinding device 21 is now described. Initially, reel 1 is mounted on therotating shaft of motor 22 and a tip of superabrasive wire saw 10 isfixed on one end 3 of peripheral surface 2. Motor 22 is then driven torotate reel 1 so that superabrasive wire saw 10 guided by traverser 24is wound around peripheral surface 2. At this stage, based on therotating rate of motor 22, the controller, which is not shown, indicatesto motor 25 an appropriate rotating rate and a timing of reversing therotating direction to be taken. As a result, traverser 24 reciprocatesat a constant rate, and superabrasive wire saw 10 is woundreciprocatingly between one end 3 and the other end 4 to bemulti-layered with pitch P satisfying the relation of D<P<2D.

Alternatively, based on winding tension T of superabrasive wire saw 10measured by tension meter 23, the controller, which is not shown, mayindicate to motor 22 an appropriate rotating rate to be taken. In thiscase, the controller, which is not shown, indicates a rotating rate ofmotor 22 to be taken such that winding tension T corresponds to 5% to50%, both inclusive, of the breaking strength of superabrasive wire saw10. In doing so, superabrasive wire saw 10 once wound can be preventedfrom loosening. At the same time, damage to bonding material 12 due toengagement of wound superabrasive wire saws 10 can be prevented.

More preferably, the rotating rate of motor 22 is controlled such thatwinding tension T corresponds to 5% to 30%, both inclusive, of thebreaking strength of superabrasive wire saw 10. Still more preferably,the rotating rate of motor 22 is controlled such that winding tension Tcorresponds to 10% to 20%, both inclusive, of the breaking strength ofsuperabrasive wire saw 10.

With the superabrasive wire saw-wound structure and the method ofwinding a superabrasive wire saw configured as such, superabrasive wiresaw 10 is wound with pitch P satisfying the relation of D<P. Therefore,when superabrasive wire saw 10 is wound around reel 1, adjacentsuperabrasive wire saws 10 (for example, superabrasive wire saws 102 band 102 c in FIG. 4) do not cause a friction therebetween. Sincesuperabrasive wire saw 10 is wound with pitch P satisfying the relationof P<2D, superabrasive wire saw 10 which is being wound does not enter agap between superabrasive wire saws 10 adjacent with each other in thelower layer (for example, superabrasive wire saw 102 b does not enter agap between superabrasive wire saw 101 c and superabrasive wire saw 101d in FIG. 4). In doing so, damage to bonding material 12 ofsuperabrasive wire saw 10 and falling of superabrasive grains 13 can beprevented.

As a winding device for producing a superabrasive wire saw winding, thepresent embodiment uses horizontal-type winding device 21 with whichsuperabrasive wire saw 10 is wound around reel 1 reciprocatingly in ahorizontal direction. However, there may be used any winding device withwhich superabrasive wire saw 10 is wound in any other direction such asa vertical-type winding device with which superabrasive wire saw 10 iswound in a vertical direction. Note that since the use ofhorizontal-type winding device 21 is not affected by gravity,superabrasive wire saw 10 does not slide over peripheral surface 2 ofreel 1, which results in easy winding thereof with predetermined pitchP.

Second Embodiment

A superabrasive wire saw-wound structure according to the secondembodiment of the present invention basically has a structure similar tothat of the first embodiment. The description of the overlappingstructure thereof will not be repeated herein.

According to the present embodiment, superabrasive wire saw 10 is woundaround peripheral surface 2 of reel 1 with pitch P further satisfying arelation of 1.1D<P<(3^(1/2)) D. More preferably, pitch P satisfies arelation of 1.2D<p<(3^(1/2)) D. With the superabrasive wire saw-woundstructure configured as such, the effects which will be described belowcan be obtained in addition to the effects of the first embodiment.

Referring to FIG. 6, over a superabrasive wire saw 31 a wound in an n-thlayer, a superabrasive wire saws 31 b and 31 c are wound in an (n+1)-thlayer and a superabrasive wire saw 31 d is wound in an (n+2)-th layer.These superabrasive wire saws are wound with pitch P satisfying arelation of P=(3^(1/2)) D.

In this case, the angle α shown in FIG. 6 is 30°, and superabrasive wiresaw 31 d wound in the (n+2)-th layer is in contact with superabrasivewire saws 31 b and 31 c wound in the (n+1)-th layer, and superabrasivewire saw 31 a wound in the n-th layer as well. Such contacts increasethe risk of damage to bonding material 12 of superabrasive wire saw 31a. If the superabrasive wire saw is wound with pitch P satisfying arelation of P>(3^(1/2)) D, superabrasive wire saw 31 d is in contactwith superabrasive wire saw 31 a only. In this case, the superabrasivewire saw becomes unstable in its wound state, which results in the riskof fluctuations in winding pitch.

Therefore, with the superabrasive wire saw-wound structure in thepresent embodiment, damage to bonding material 12 and falling ofsuperabrasive grains 13 can further be reduced, and superabrasive wiresaw 10 can be wound around reel 1 without any fluctuations in windingpitch.

Third Embodiment

Referring to FIG. 7, a cutting device with a superabrasive wire saw 51(hereinafter referred to “cutting device 51”) includes a superabrasivewire saw supplier 57 reeling and unreeling superabrasive wire saw 10 toand from a workpiece 55. Superabrasive wire saw supplier 57 is providedwith reel 1 having superabrasive wire saw 10 wound by using thesuperabrasive wire saw-wound structure according to the first or secondembodiment. Two reels 1 are placed on respective lateral sides withrespect to workpiece 55 and mounted on the rotating shafts of themotors, respectively.

Cutting device 51 further includes a plurality of guide rollers 52 and53 guiding superabrasive wire saw 10, two main rollers 56 placed underworkpiece 55 at a predetermined spacing, and two cutting fluid nozzles54 provided in the vicinity of main rollers 56, respectively. Groovesare provided on a peripheral surface of main roller 56 according to acutting size of workpiece 55. Superabrasive wire saw 10, with both endsthereof wound around two reels 1, respectively, is guided by the grooveto be stretched taut between two main rollers 56. Guide roller 52 isprovided such that it can reciprocate in a predetermined direction.

When workpiece 55 is cut with cutting device 51, the motor to which reel1 is connected is rotated in forward/reverse direction, which causessuperabrasive wire saw 10 to reciprocate between two reels 1. At thisstage, guide roller 52 may be reciprocated in a manner similar to thatof traverser 24 shown in FIG. 5. In doing so, even in a cutting processusing cutting device 51, superabrasive wire saw 10 is wound around reel1 with predetermined pitch P, with the result that the effects similarto those of the first or second embodiment can be obtained.

Thereafter, workpiece 55 is pressed against a plurality of superabrasivewire saws 10 moving between two main rollers 56. In doing so, workpiece55 can be cutting-processed into a plurality of pieces. In the process,a cutting fluid is supplied through cutting fluid nozzles 54 toworkpiece 55 and the grooves formed on the peripheral surface of mainroller 56. The cutting fluid serves to reduce a friction in a cuttingprocess and promote cooling. When guide roller 52 is reciprocated suchthat superabrasive wire saw 10 is wound with predetermined pitch P, acutting fluid supplied in the cutting process exists in a gap betweensuperabrasive wire saws 10 wound around reel 1. Therefore, it isbelieved that the above-described effects by the cutting fluid can beobtained much more effectively.

With the cutting device with a superabrasive wire saw configured assuch, since superabrasive wire saw 10 wound with predetermined pitch Pis used, damage to bonding material 12 and falling of superabrasivegrains 13 are prevented even when superabrasive wire saw 10 is unreeledagain from reel 1. Therefore, workpiece 55 can be cut extremely cleanly,and the life of superabrasive wire saw 10 can be prolonged. If guideroller 52 is reciprocated such that superabrasive wire saw 10 is woundwith predetermined pitch P, damage to bonding material 12 and falling ofsuperabrasive grains 13 can be reduced even when a cutting processcontinues.

In order to evaluate the superabrasive wire saw-wound structure and themethod of winding a superabrasive wire saw according to the presentinvention, examples and comparative examples are provided, which will bedescribed below.

EXAMPLE 1

By using cutting device 51 in FIG. 7, a test was conducted to examineinfluences of winding pitch P of superabrasive wire saw 10 on damage tobonding material 12 and falling of superabrasive grains 13. A piano wirehaving average diameter d1 of 0.18 mm was used as core wire 11 ofsuperabrasive wire saw 10. Diamond superabrasive grains having averagediameter d2 of 42 μm were used as superabrasive grains 13. A phenolresin was used as bonding material 12. Average diameter D ofsuperabrasive wire saw 10 was 0.25 mm.

Under the test conditions below, there was conducted an unreeling testin which superabrasive wire saw 10 was repeated1y reciprocated betweentwo reels 1.

Test Conditions:

Rate of superabrasive wire saw; 800 m/min

Winding tension T; 9.8N

Winding pitch P; 0.4 mm (D<P<2D)

Cutting fluid; water-soluble cutting fluid

Unreeling cycle (one reciprocation is defined as one cycle); 212 cycles

After the test, superabrasive wire saw 10 having a length ofapproximately 82 m and stretched taut between two main rollers 56 wasobserved under a microscope to determine a cumulative peel length ofbonding material 12 and check for falling of superabrasive grains 13.The result showed that a cumulative peel length of bonding material 12was 50 mm and that almost no falling of superabrasive grains 13 wasobserved.

Comparative Example 1

By using superabrasive wire saw 10 specified similarly to that ofexample 1, an unreeling test was conducted according to the testconditions of example 1 with the exception that only winding pitch Pthereamong was set to 0.2 mm (P<D). After the test, the observation ofsuperabrasive wire saw 10 as in example 1 showed that a cumulative peellength of bonding material 12 was 250 mm and that falling ofsuperabrasive grains 13 was observed.

Comparative Example 2

By using superabrasive wire saw 10 specified similarly to that ofexample 1, an unreeling test was conducted according to the testconditions of example 1 with the exception that only winding pitch Pthereamong was set to 0.6 mm (P>2D). After the test, the observation ofsuperabrasive wire saw 10 as in example 1 showed that a cumulative peellength of bonding material 12 was 280 mm and that falling ofsuperabrasive grains 13 was observed.

EXAMPLE 2

Next, by using superabrasive wire saw 10 specified similarly to that ofexample 1, an unreeling test was conducted under the test conditionsbelow to examine the effects of the change in winding tension T ofsuperabrasive wire saw 10. Note that a tensile test was performed onsuperabrasive wire saw 10 in advance, showing that the breaking strengththereof was 78N.

Test Conditions:

Rate of superabrasive wire saw; 800 m/min

Winding tension T; 9.8N (corresponding to 12.6% of the breaking strengthof superabrasive wire saw 10)

Winding pitch P; 0.4 mm (D<P<2D)

Cutting fluid; water-soluble cutting fluid

Unreeling cycle; 424 cycles

After the test, the observation of superabrasive wire saw 10 as inexample 1 showed that a cumulative peel length of bonding material 12was 350 mm.

EXAMPLE 3

By using superabrasive wire saw 10 specified similarly to that ofexample 1, an unreeling test was conducted according to the testconditions of example 2 with the exception that only winding tension Tthereamong was set to 25.7N (corresponding to 33% of the breakingstrength of superabrasive wire saw 10). After the test, the observationof superabrasive wire saw 10 as in example 1 showed that a cumulativepeel length of bonding material 12 was 2300 mm.

EXAMPLE 4

By using superabrasive wire saw 10 specified similarly to that ofexample 1, an unreeling test was conducted according to the testconditions of example 2 with the exception that only winding tension Tthereamong was set to 29.4N (corresponding to 37.7% of the breakingstrength of superabrasive wire saw 10). After the test, the observationof superabrasive wire saw 10 as in example 1 showed that a cumulativepeel length of bonding material 12 was 4120 mm.

Comparative Example 3

By using superabrasive wire saw 10 specified similarly to that ofexample 1, an unreeling test was conducted according to the testconditions of example 2 with the exception that only winding tension Tthereamong was set to 39.2N (corresponding to 52% of the breakingstrength of superabrasive wire saw 10). After the test, the observationof superabrasive wire saw 10 as in example 1 showed that a cumulativepeel length of bonding material 12 was 6530 mm.

Comparative Example 4

By using superabrasive wire saw 10 specified similarly to that ofexample 1, an unreeling test was attempted according to the testconditions of example 2 with the exception that winding tension Tthereamong was set to 3N (corresponding to 3.8% of the breaking strengthof superabrasive wire saw 10). In this case, however, superabrasive wire10 loosened while it was being wound around reel 1, which resulted in acancellation of the test.

Although the present invention has been described and illustrated indetail, it is clearly understood that the same is by way of illustrationand example only and is not to be taken by way of limitation, the spiritand scope of the present invention being limited only by the terms ofthe appended claims.

INDUSTRIAL APPLICABILITY

The present invention is employed for a bonded-abrasive typesuperabrasive wire saw used for slicing a silicon ingot into siliconwafers, and performing a cutting process on various materials such asmetal, resin, ore, glass, sapphire, rock crystal, SiC, and compoundsemiconductor.

1. A superabrasive wire saw-wound structure comprising: a superabrasivewire saw formed with an average diameter D and including a core wire, abonding material surrounding a surface of said core wire, and aplurality of superabrasive grains bonded to the surface of said corewire with said bonding material; and a reel portion including aperipheral surface having one end and the other end, said superabrasivewire saw to be unreeled successively toward a workpiece being woundaround said peripheral surface reciprocatingly between said one end andsaid other end to be multi-layered, wherein a pitch P for winding saidsuperabrasive wire saw around said peripheral surface between said oneend and said other end satisfies a relation of 1.1D<P<(3^(1/2)) D. 2.The superabrasive wire saw-wound structure according to claim 1, whereineach of said superabrasive grains is provided to partly project from asurface of said bonding material.
 3. The superabrasive wire saw-woundstructure according to claim 1, wherein said pitch P further satisfies arelation of 1.2D<P<(3^(1/2)) D.
 4. The superabrasive wire saw-woundstructure according to claim 1, wherein said core wire having an averagediameter d1, each of said superabrasive grains having an averagediameter d2, and the average diameters d1 and d2 satisfy a relation of0.02<d2/d1<0.5.
 5. The superabrasive wire saw-wound structure accordingto claim claim 1, wherein said bonding material includes at least oneselected from the group consisting of a resin bond, anelectrodeposition, a metal bond, and a vitrified bond.
 6. Thesuperabrasive wire saw-wound structure according to claim claim 1,wherein said bonding material is a resin bond.
 7. The superabrasive wiresaw-wound structure according to claim 1, wherein said bonding materialincludes at least one selected from the group consisting of alkyd resin,phenol resin, formalin resin, polyurethane resin, polyester resin,polyimide resin, epoxy resin, melamine resin, urea resin, unsaturatedpolyester resin, acrylic resin, polyesterimide resin, polyamid-imideresin, polyester urethane resin, bismaleimide resin, bismaleimidetriazine resin, cyanato ester resin, polyetherimide, polyparabanic acid,and aromatic polyamide.
 8. A cutting device with a superabrasive wiresaw comprising a superabrasive wire saw supplier provided by using thesuperabrasive wire saw-wound structure recited in claim
 1. 9. A methodof winding a superabrasive wire saw comprising the steps of: preparing asuperabrasive wire saw formed with an average diameter D and including acore wire, a bonding material surrounding a surface of said core wire,and a plurality of superabrasive grains bonded to the surface of saidcore wire with said bonding material, and a reel portion including aperipheral surface having one end and the other end; and winding saidsuperabrasive wire saw around said peripheral surface reciprocatinglybetween said one end and said other end to be multi-layered, whereinsaid step of winding said superabrasive wire saw includes the step ofwinding said superabrasive wire saw such that a pitch P for winding saidsuperabrasive wire saw between said one end and said other end satisfiesa relation of 1.1D<P<(3^(1/2))D.
 10. The method of winding asuperabrasive wire saw according to claim 9, wherein each of saidsuperabrasive grains is provided to partly project from a surface ofsaid bonding material.
 11. The method of winding a superabrasive wiresaw according to claim 9, wherein said step of winding saidsuperabrasive wire saw includes the step of winding said superabrasivewire saw such that said pitch P satisfies a relation of 1.2D<P<(3^(1/2))D.
 12. The method of winding a superabrasive wire saw according to claim9, wherein said core wire having an average diameter d1, each of saidsuperabrasive grains having an average diameter d2, and the averagediameters d1 and d2 satisfy a relation of 0.02<d2/d1<0.5.
 13. The methodof winding a superabrasive wire saw according to claim 9, wherein saidstep of winding said superabrasive wire saw includes the step of windingsaid superabrasive wire saw with winding tension corresponding to 5% to50%, both inclusive, of a breaking strength of said superabrasive wiresaw.
 14. The method of winding a superabrasive wire saw according toclaim 13, wherein said step of winding said superabrasive wire sawincludes the step of winding said superabrasive wire saw with windingtension corresponding to 10% to 20%, both inclusive, of a breakingstrength of said superabrasive wire saw.
 15. The method of winding asuperabrasive wire saw according to claim 9, wherein said bondingmaterial is a resin bond.
 16. The method of winding a superabrasive wiresaw according to claim 9, wherein said bonding material includes atleast one selected from the group consisting of alkyd resin, phenolresin, formalin resin, polyurethane resin, polyester resin, polyimideresin, epoxy resin, melamine resin, urea resin, unsaturated polyesterresin, acrylic resin, polyesterimide resin, polyamid-imide resin,polyester urethane resin, bismaleimide resin, bismaleimide triazineresin, cyanato ester resin, polyetherimide, polyparabanic acid, andaromatic polyamide.